New biochar-based technology boosts antibiotic removal from water using low-energy ultrasound

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Researchers have developed a new carbon-based material that dramatically improves the removal of persistent antibiotics from water, offering a promising and energy-efficient solution to a growing environmental challenge.

Antibiotics such as enrofloxacin and amoxicillin are widely used in human and veterinary medicine, but their residues often accumulate in wastewater and natural environments. These compounds are difficult to degrade and can contribute to antibiotic resistance and ecological risks. Conventional treatment methods, including ultrasound alone, often require high energy input but still achieve limited removal efficiency.

In a new study, scientists designed a novel composite material that combines biochar, carbon nanotubes, and iron carbide into a single structure. When paired with low-frequency ultrasound, the material significantly accelerates the breakdown of antibiotics in water.

“Our goal was to create a material that not only adsorbs antibiotics but also actively promotes their degradation under mild conditions,” said one of the study’s lead authors. “By integrating biochar with carbon nanotubes and iron, we were able to enhance both the efficiency and sustainability of the process.”

The newly developed material, referred to as a biochar-based solid cavitation material, works by amplifying the physical and chemical effects generated during ultrasound treatment. When ultrasound waves pass through water, they create tiny bubbles that rapidly collapse, producing localized high temperatures and reactive species capable of breaking down pollutants. However, this process is typically inefficient at low frequencies.

The researchers found that their material significantly enhances this cavitation effect. The biochar component increases hydrophobicity and surface stability, allowing more cavitation bubbles to form and persist on the material surface. At the same time, carbon nanotubes and iron sites facilitate chemical reactions that generate reactive oxygen species, which further degrade antibiotic molecules.

As a result, the system achieved up to 15 times higher removal rates compared to conventional materials. More than 90 percent of both enrofloxacin and amoxicillin were removed within several hours under low-frequency ultrasound, while requiring substantially less energy than traditional approaches.